PTGS2 and lung cancer: Despite our data of lung cancer cells showing that NCX4040 significantly decreases PGE2 levels after 4 h of exposure, the EC50 values obtained in three different NSCLC lines (Figure 3, lower row) are consistent with previous data, as the two more resistant cell lines (A549 and H1299) expressed higher levels of COX-2 than the H1975 cell line [42].